1. Field of the Invention
The present invention relates to a scanning probe microscope (SPM), and more particularly, to an SPM which precisely analyzes characteristics of samples having an overhang surface structure.
2. Description of the Related Art
Scanning probe microscopes (SPMs) have nano-scale resolution in order to show the shape of a surface of a sample or an electrical characteristic of the sample as an image. SPMs include atomic force microscopes (AFMs), magnetic force microscopes (MFMs), and scanning capacitance microscopes (SCMs). SPMs are used to analyze the shape of a surface of a sample or an electrical characteristic of the sample by moving a tip of a probe in contact with the surface of the sample or by moving the tip of the probe at a predetermined distance above the surface of the sample. However, in the case of a conventional scanning probe microscope, there is a problem in that the shape of a surface of a sample or an electrical characteristic of the sample cannot be precisely analyzed on a specific surface shape of the sample.
FIG. 1 is a schematic perspective view of a conventional scanning probe microscope. Referring to FIG. 1, a first scanner 31 and a second scanner 32 are attached to a frame 50. That is, the first scanner 31 is attached to a first frame 51 and the second scanner 32 is attached to a second frame 52. A probe 10 is attached to an end of the first scanner 31 and the first scanner 31 moves the probe 10 in a ±z-direction. A stage 20 is provided on the second scanner 32 and the second scanner 32 moves the stage 20 on an xy-plane. When a sample is disposed on the stage 20, the first scanner 31 moves the probe 10 in the ±z-direction and the second scanner 32 moves the stage 20, that is, the sample, on the xy-plane so that data related to the shape of a surface of the sample or an electrical characteristic of the sample can be obtained.
FIG. 2A is a schematic conceptual view for the case of analyzing a sample using the scanning probe microscope of FIG. 1, FIG. 2B is a schematic conceptual view of the shape of a surface of the sample obtained by analysis performed in FIG. 2A, FIG. 3A is a schematic conceptual view for the case of analyzing another sample using the scanning probe microscope of FIG. 1, and FIG. 3B is a schematic conceptual view of the shape of a surface of the sample obtained by analysis performed in FIG. 3A.
Referring to FIGS. 2A and 2B, while a probe 10 attached to a carrier 15 moves so that a predetermined distance between a tip 12 placed on an end of a cantilever 11 of the probe 10 and the surface of a sample 20 can be kept (or while the tip 12 and the surface of the sample 20 are closely attached to each other), data related to the surface shape of the sample 20 are collected. Actually, while the sample 20 moves in an xy-plane using a second scanner 32 (see FIG. 1) and the probe 10 moves on a ±z-axis indicated by l 1 using a first scanner 31 (see FIG. 1), data related to the sample 20 are collected. As a result, when the surface shape of the sample 20 is realized, the same shape 20′ as that of the sample 20 is realized, as illustrated in FIG. 2B.
However, if a sample has an overhang structure illustrated in FIG. 3A, correct data related to the sample cannot be obtained using the conventional scanning probe microscope. That is, while the probe 10 moves on the ±z-axis indicated by l 1 using the first scanner 31 (see FIG. 1), data related to the sample 20 are collected. Thus, if a side surface 20a of the sample 20 is not a surface including the ±z-axis but is an inclined surface illustrated in FIG. 3, the probe 10 cannot scan the side surface 20a of the sample 20 having an overhang structure. Accordingly, when the surface shape of the sample 20 is realized using the conventional scanning probe microscope, there is a problem in that a different shape 20′ from that of the sample 20 is realized as illustrated in FIG. 3B.
To solve this problem, a method using a probe 10 illustrated in FIG. 4 has been proposed. That is, the probe 10 has a protrusion 10a on its front end so that correct data related to a sample 20 having an overhang structure can be obtained using the protrusion 10a. However, when using the probe 10, it is not easy to manufacture the probe 10, excessive costs are required for its manufacture and the yield thereof is also low. In addition, since the probe 10 manufactured in such a way is not sharper than a conventional probe, there is a problem in that precise data related to a fine surface shape of nano-scale cannot be obtained. In the overhang structure of the sample, when the side surface 20a of the sample 20 is more inclined than the protrusion 10a of the probe 10, correct data related to the sample cannot be obtained even using the probe 10 illustrated in FIG. 4.